I. Field of the Invention
The invention relates to the implantation and placement of cardiac leads used in combination with cardiac rhythm management devices, e.g., heart pacemakers or defibrillators, to monitor and control the rhythm of the heart. This invention is more particularly directed toward a guidewire/pacing lead configuration adapted to assist in the implantation and placement of a cardiac lead having one or more electrodes that are to reside in the distal branches of the coronary venous system, the great cardiac vein, or coronary sinus. The invention also encompasses the use of a guide catheter along with a guidewire and finishing wire configurations useful in removing guide catheters without dislodging the implanted leads.
II. Discussion of the Prior Art
Placement of cardiac leads in the distal branches of the coronary venous system, the great cardiac vein, or the coronary sinus is a difficult task. Often when deploying the lead there comes a point at which the lead cannot be advanced further into the vascular system using standard techniques and equipment. All too often this point is not the optimal position for the lead's electrode, either for sensing cardiac electrical activity or delivering pacing therapy to the heart.
There are several reasons which make proper placement of the lead difficult. These include (1) friction between the vasculature and the lead; (2) partial obstruction of the vasculature; (3) unusually shaped bifurcations in the vasculature; and (4) accumulative friction between lead, guide catheter and guidewire. Prior efforts to resolve such problems included the use of a stiffer guidewire. While stiffer guidewires offer additional support, they may impede advancement due to their relative size with respect to the lumen of the lead. Additionally, when proper placement of the lead is achieved, problems arise during guide catheter or guidewire extraction. All too often, the act of extracting the guide catheter and/or guidewire causes the lead to be dislodged from the implanted position. Standard guidewires and stylets are not suitable for maintaining position while the guide catheter is removed due to insufficient stiffness, lack of appropriate force transmission features, and friction between the guidewire and lumen wall of the coronary vein lead. A means must be provided which will hold the lead and its corresponding electrodes in place while allowing the guide catheter and guidewire to be removed.
The present invention is deemed to be an improvement over conventional prior art guidewires. It is more effective in properly placing the lead and it is also less likely to cause a properly placed lead to become dislodged during extraction of the guide catheter and the guidewire itself.